Polyolefins such as polyethylene and polypropylene may be prepared in a number of ways, including by slurry polymerization. In this technique, feed materials such as diluent, monomer and catalyst are introduced to a loop reaction zone, forming a “slurry” in the reaction zone. In continuous loop reactors, the slurry circulates through the loop reaction zone with the help of a reactor circulation pump, and the monomer reacts in the presence of the catalyst in a polymerization reaction. The polymerization reaction yields solid polyolefins in the slurry. A polymerization product stream having solid polyolefins is then transferred from the reactor and separated to recover the solid polyolefins.
In general, a portion of reactor contents (e.g., polymerization product) can be removed from the reactor to control reactor pressure, which in turn could lead to fluctuations in reactor circulation pump power. Pump power fluctuations could have adverse effects on polyolefin production.